Loreley has never (see below) been used as a personal name in Germany. It's the name of a slate rock on the river Rhine (near St. Goarshausen). It means something like "slate rock as a lookout". This name has been misinterpreted following the name LORE, and thus the whole story came up: It was Brentano who first wrote (down) the legend of the beautiful girl with the long blond hair.